Is it permissible to collect firewood from abandoned agricultural lands where acacia trees grew, then died and fell, knowing that their owners are unaware of their property and its landmarks have been obliterated?

It is permissible for a Muslim to gather firewood from trees that grow naturally, without cultivation or care, even if they are on private property. The landowner is not permitted to prevent Muslims from doing so unless he is in need of them. If he is not in need, then Muslims are partners in them, and whoever gets to them first has a greater right to them, based on the hadith (definition): "Muslims are partners in three things: pasturage, water, and fire." The meaning of the hadith refers to what grows on owned land naturally, without effort from its owner. Allah has forbidden whoever withholds the bounty of what his hands did not produce.